Starting and operating circuits and devices for electric discharge devices



Feb. 19, 1952 p w -r 2,586,400

STARTING AND OPERATING CIRCUITS AND DEVICES FOR ELECTRIC DISCHARGE DEVICES Filed May 20, 1948 Hi1. 2aa 2 lnven cor PhiLippe Wa cguefi b5 UWC k His A=tl70r neg Patented Feb. 19, 1952 STARTING AND OPERATING CIRCUITS AND DEVICES FOR ELECTRIC DISCHARGE DE- VICES' Philippe Waguet, Paris, France, assignor to General Electric Company, a corporation of New York Application May 20, 1948, Serial No. 28,224.

In France June 14, 1947 2 Claims. 1

This invention relates to electric discharge devices of the type employing ionizable mediums such as gases or vapors, and more particularly to starting and operating devices and circuits therefor.

An object of my invention is to provide new and improved starting and operating circuits for electric discharge lamps energized from direct current sources.

Another object of my invention is to provide a new and improved starting and operating circuit for luminous electric discharge devices or fluorescent lamps energized in parallel from a direct current source. A feature of my invention is the provision of a single voltage impulse to an auxiliary electrode for initiating a discharge be tween the main electrodes of the devices, and a further feature is the utilization of alternating current derived from the direct current for heating the filamentary electrodes.

My invention is of general applicability wherever it is desired to operate fluorescent lamps from a direct current supply, and it has been found particularly useful in the illumination of vehicles and railroad cars. For a more complete discussion of various circuits which may be employed in operating fluorescent lamps from a direct current supply, reference is made to my copending U. S. application No. 28,223, filed May 20,

1948. Other uses of, and improvements in such circuits are disclosed in my copending U. S. applications Nos. 28,225 and 28,226, filed May 20, 1948, and 33,385, 33,386 and 33,387, filed June 16, 1948. All of the above-mentioned applications are assigned to the same assignee as the present invention.

For a better understanding of my invention reference may be had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims. Fig. 1 is a diagrammatic view of a pair of electric discharge devices and starting and operating circuits therefor incorporating my invention wherein the devices are ignited or extinguished simultaneously. Fig. 2 illustrates a variation of the circuit shown in Fig. 1 wherein the devices may be ignited or extinguished separately.

In accordance with my invention, I have provided a means of imparting temporarily to an auxiliary electrode in the vicinity of an electric discharge lamp a starting potential exceeding that of the anode or less than that of a filamentary electrode serving as a cathode and, in V addition, permitting the use of an alternating current energized equipotential filamentary electrode for the cathode. The discharge circuit connected to an electric discharge lamp operating on a direct current supply may thus be connected to the center point or tap of a heating coil for the cathode, regardless of whether the heating is dispensed with during the operation of the lamp or not.

These circuits are useful in particular for the lighting of cars, especially of railway cars such as the one to which Fig. 1 applies, where the heating of the cathode filaments is automatically suppressed after the lighting of lamps (as is the case in cars without compartments), or the one to which Fig. 2 applies Where the heating of the filament continues after the lighting of the lamps, so as to permit the instantaneous relighting of every one of them (as is the case in cars with' compartments).

Referring to Fig. 1, I have there illustrated one embodiment of my invention as applied to electric discharge devices I, I connected in parallel. The electric discharge devices I I such as fluorescent lamps, therein illustrated comprise elongated tubular or cylindrical envelopes 2, 2 having sealed into the ends thereof thermionic filamentary electrodes 3, 4 and 5, 6. Filamentary electrodes 3, 4 and 5, 6 may comprise coils, preferably in the form of coiled coils of tungsten wire activated with oxides of alkaline earth metals such as mixtures of barium and strontium oxides. The envelopes 2, 2' may contain gaseous atmospheres of rare gases such as neon, argon or mixtures thereof at a pressure of a few millimeters and a small quantity of mercury which, during the operation of the lamps, has a low pressure of the order of 10 microns. Devices I, I may be low pressure positive column lamps of a fluorescent type provided with a suitable phosphor or fluorescent coating. This fluorescent coating, upon excitation by the radiation produced by an electric dischargeibetween the electrodes, transforms a shorter wave radiation due to the discharge into longer wave radiation, such as radiation within the visible range. A pair of metal cups 1, 8 and 9, [U for each device I and I serve to intercept particles of emissive material sputtered from electrodes 3, 4 and 5, 6 respectively. These cups are usually connected, either outside or inside of the lamps, to the extremities of electrodes 3, 4 and 5, 6; A number of advantages result from the connections between filamentary electrodes 3, 4 and 5, 6 and the corresponding cups 1, 8 and 9, [0, namely, utilization of cups 8 and H) as anodes and elimination of the disintegration by ionic bombardment of filamentary electrodes 4 and 6, utilization of lamps that are usually employed with alternating current discharge circuits, reduction of operating voltage, doubling the life of lamps by using successively the two filamentary electrodes, i. e., by turning the lamps around when one of the filaments becomes inoperative.

Devices I, I are connected across a suitable direct current power supply I l H for supplying current thereto through stabilizing resistances l2 and I2. Resistances I2, l2, for example, may be iron or tungsten wires enclosed in hydrogen. A manual make-and-break switch I3 has contactors l3a and l3b for opening and closing the direct current supply and an alternating current supply, respectively, and connects devices I, I to the various sources of supply simultaneously. A starting circuit l4, I4 is connected across the direct current supply H, H and comprises an inductance IS, a contactor or switch 16, and a resistance ll. Auxiliary electrodes l8 and I8, mounted adjacent devices I, I, respectively, are connected to a common point l9 intermediate inductance I and contactor or switch 16. Resistance I1 serves to regulate the value of the potential which the auxiliary electrodes l8, l8 assume temporarily.

A transformer comprising a primary winding section 2! and a center-tapped secondary winding section 22 is connected across an alternating current supply 23, 23 and serves to heat filamentary electrodes 3 and 5 of devices I, I, respectively. The center tap of secondary winding section 22 is connected to the negative side ing section 2| of transformer 20 in turn is connected to the terminals of the auxiliary alternating current supply 23, 23 by means of contactor l3b of switch l3 and a second contactor or switch 24. Contactors or switches i6 and 24 may be operated simultaneously and automatically by the use of a time-delay relay 25 comprising a coil 26 connected directly across the direct current supply H, II at points 21, 21'. A pair of fuses 28 and 29 protect the elements of the heating transformer 20 in the case of a short circuit in the thermo-emissive filamentary electrodes 3 and 5.

The device illustrated in Fig. l Operates as follows: In the rest position, the contacts IE and 24 of the time-delay relay are closed; as soon as the double-pole feeder switch I3 is closed the cathode filamentary heated, the inductance i5 is magnetized and the coil 26 of the time-delay relay 25 is energized. After one or more seconds this relay operates and opens the contacts 16 and 24, which opening ignites the tubes and interrupts the current which heats the filaments.

In Fig. 2, where the corresponding elements which Figs. 2 and 1 have in common are denoted by the same numerals, the primary winding 2! of the heating transformer 20 is connected to a converter 30 which is energized through a manual make-and-break switch 3i, by the direct current source H, H. The contacts l6, 16' of relays 25 and 25 are controlled by the windings 26, 26', which in turn are connected to the terminals H, II' of the direct current source by means of operating switches 32, 32' and contact switch 33 of a time-delay relay 34. Time-delay relay 34, in addition, comprises a coil 35 which electrodes 3 and 5 are is connected across the terminals of the direct current source II, II.

In Fig. 2 the device operates as follows: In the rest position, with contacts l6, [6' closed and contact 33 open, as soon as feeder switch 3| is closed the converter 30 starts, the cathode filaments 3 and 5 are heated and coil 35 of the time-delay relay 34 is energized. After one or more seconds this relay functions and closes the contact switch 33. In the case of lamps whose operating switches such as 32, 32 are closed, the inductances such as [5, l5 are magnetized and the coils such as 26, 26 of relays 25, 25 are energized. These relays function to open the contacts I6, 16, which brings about the ignition of the corresponding discharge lamps.

Inasmuch as the filaments such as 3 and 5 are all continuously heated, the devices like I, I, whose operating switches such as 32, 32' are open, can now be instantaneously ignited upon the closing of their operating switches.

It is quite evident that the invention may be applied to purposes other than those which have just been considered for the lighting of railway cars; it may be applied also particularly well to the lighting of motion picture and television studios, wherein it is desirable, under certain circumstances, to utilize direct current for fluorescent lighting rather than alternating current so as to eliminate the possibility of stroboscopic flickering. The appended claims are, therefore intended to cover any modifications coming within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for operating a gaseous luminous electric discharge device, of the type including a main filamentary electrode and a cooperating main electrode, comprising: a unidirectional voltage source, an auxiliary dependent source of alternating voltage: a discharge circuit including said device, ballast resistance and a control switch connected in series across said unidirectional source; connections for providing heating current to said filamentary electrode from said alternating voltage source; means for energizing said alternating voltage source whenever said discharge circuit is connected to said unidirectional source, said filamentary electrode thereby becoming heated, independently of the state of conduction within said device; a starting circuit comprising a resistance, a normally closed contact of a time-delay relay, and an inductance, serially connected across said unidirectional source through said control switch; auxiliary starting electrode for said device connected to the junction of said contact with said inductance; and means for making said time-delay relay dependent, as to its operation, upon the closing of said control switch, whereby said contact opens at a predetermined time interval after the closing of said control switch and a single starting impulse is provided thereupon at said starting means.

2. Apparatus for operating a gaseous luminous electric discharge device of the type including a main filamentary electrode and a cooperating main electrode, comprising: a source of unidirectional voltage, an auxiliary dependent source of alternating voltage; a discharge circuit including said device, a ballast resistance and a control switch connected in series across said unidirectional source; connections for providing heating current to said filamentary electrode from said alternating voltage source; means for energizing said alternating voltage source whenthereby becoming heated, independently of the state of conduction within said device; a starting circuit comprising a resistance, a normally closed contact of a time-delay relay, and an inductance, serially connected across said unidirectional source through said control switch; an auxiliary starting electrode in said device connected to the junction of said contact with said inductance; and a circuit for; the coil of said time-delay relay through said control switch for opening said contact at a predetermined time interval after the closing of said control switch, whereby a single starting impulse is provided at said auxiliary electrode through the rupturing of said starting circuit.

PHILIPPE WAGUE'I.

The following references are of record in the 1 REFERENCES CITED 5 file of this patent:

Number 15 Number UNITED STATES PATENTS Name Dat Wiegand Feb. 9, 1932 Erickson Oct. 16, 1934 Lederer Nov. 12, 1935 McKesson Mar. 25, 1941 Lord Aug. 19, 1941 Campbell Dec. 21, 1948 FOREIGN PATENTS Country Date France Oct. 22, 1940 

